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Thursday, August 21, 2008

Cholesterol lowering drugs already known to be linked with cancer

At the FDA one wonders exactly how out of touch they can be. The cancer link to this class of drug is well established. Maybe more effort should be placed on getting them off the market once and for all.

Cholesterol drugs don't protect against cancer Statins do not reduce the risk of cancer, finds a review of several long-term studies published today.

The findings contradict previous studies, which suggested that the cholesterol-lowering drugs reduce cancer risk. They are based on 26 randomized controlled trials of statins and cancer incidence, or cancer death, including a total of 86,936 participants.

Dr C. Michael White and colleagues at the University of Connecticut and Hartford Hospital, Hartford, USA, report the findings in today's issue of the Journal of the American Medical Association.

They write: "In the trials, statins reduced the risk of a first myocardial infarction [heart attack] and overall mortality. With long-term follow-up and collection of cancer data in a majority of studies, insight into the risk of cancer among statin-naive persons and statin users can be derived.*

"In our current meta-analysis, statins did not reduce the incidence of cancer or cancer death." JAMA. 2006; 295: 74-80.

And now another MD concurs...Low cholesterol levels linked with increased risk of cancer, so is cholesterol reduction safe?Dr John Briffa, August 22, 2008

When in comes to cholesterol levels, the mantra is usually ‘the lower the better’. The idea here is that the lower the level of cholesterol in our bloodstreams, the lower our risk of cardiovascular disease (e.g. heart attack and stroke) and therefore, we hope, death from these conditions. But wait a minute, even if this were true, how about if lower levels of cholesterol actually increased our risk of other important conditions? Might an increased risk of, say, cancer, offset any apparent advantages of low cholesterol with regard to cardiovascular disease.

This is not just theory: evidence shows that the lower cholesterol levels are, generally speaking, the higher the risk of cancer. The most recent study to show this association was published this week in the Journal of the American College of Cardiologists (JACC). The study was designed to assess the risk of cancer in individuals taking statin (cholesterol-lowering drugs). In this study, the results of 15 statin studies were assessed.

The researchers found, as had been noted before, that in individuals in these studies taking placebo, the lower their cholesterol levels, the higher their risk of cancer. They also found the same thing in individuals taking statins in these studies. But, for a given cholesterol level, statin takers were, overall, not found to be at an increased risk of cancer compared to those taking placebo.

This study led to proclamations in the press that statins do not cause cancer. And that might be true. But it might not be true too.

Let’s imagine for a moment that low cholesterol levels are not just associated with cancer but actually cause cancer. And let’s imagine that through their cholesterol-reducing capacity statins can therefore enhance cancer risk. Well, it likely takes some time for statins to reduce cholesterol and almost certain even longer for that to manifest as full-blown, diagnosable cancer. In other words, the statin trials may simply not have gone on long enough for the long-terms effects on cancer to be properly assessed.

Looking at individual studies within the review we find that some studies show no statistically significant increased risk of cancer in statin takers. Some studies even showed a reduced risk of cancer. But, and this is important I think, some individuals studies did show an increased risk of cancer in those taking statins. The results of these studies can of course be diluted by the other studies, but they are still there, and some would argue that their presence casts a pretty ominous shadow over statin and perhaps cholesterol-reducing therapy generally. The authors of an accompanying editorial in the same edition of JACC point out that the results of the review are not definitive, and don’t prove that reducing cholesterol levels down to low levels is safe as far as cancer is concerned.

Not so long ago I reported on a study (the so-called [1] SEAS study) which found that treatment with two cholesterol reducing drugs led to an increased risk of cancer compared to placebo. As even the authors of the JACC review conclude, further studies of longer duration are needed to assess the risk of cholesterol reducing medicine with regard to cancer risk.

ReferencesAlawi A, et al. Statins, Low-Density Lipoprotein Cholesterol, and Risk of Cancer. Journal of the American College of Cardiologists. Published on-line 20th August 2008.

However, the Food and Drug Administration said patients should not stop taking Vytorin because the evidence of a cancer link is unclear. While one recent clinical trial indicated higher rates of cancer for patients taking the medication, two studies currently under way have shown no increased risk.

Vytorin, a combination of Merck's Zocor and Schering-Plough's Zetia, has been heavily promoted as a novel way to reduce cholesterol. Zocor, a statin drug, reduces the amount of cholesterol produced by the liver. Zetia limits the amount of cholesterol absorbed through the digestive system. But the combination became a focus of controversy after a study earlier this year showed it was no better at reducing the buildup of plaque in the arteries than the much cheaper generic Zocor.

Statins lower the levels of LDL-cholesterol, also called 'bad' cholesterol because of its role in heart disease. Some previous studies of statins have suggested a link between low LDL levels and a higher risk of cancer. But again, others have not.

Just this week, the Journal of the American College of Cardiology published a new analysis of 15 statin studies including more than 90,000 patients that found statin users were no more likely to get cancer than people given dummy drugs.

"Nobody should avoid taking a statin because of concerns about cancer," said American Cancer Society epidemiologist Eric Jacobs.

Ironically, statins a few years ago were being studied as a possible prevention for certain cancers; those studies ultimately found no effect on cancer, good or bad.

1 comment:

A reader writes to say that he was diagnosed with borderline high cholesterol, and his doctor was strongly suggesting he start on statin. He tried a therapeutic nutritional alternative and his cholesterol levels are welll within target ranges — although not yet optimum.

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